Sequence‐regulated oligomers and polymers by living cationic polymerization. III. Synthesis and reactions of sequence‐regulated oligomers with a polymerizable group

New sequence‐regulated macromonomers (3) with a vinyl ether terminal were prepared by the HI/ZnI2‐mediated living cationic polymerization of vinyl ethers: CH3CH(OR1)CH2CH(OR2)C(COOEt)2CH2CH2OCHCH2 (3a: R1 = nBu, R2 = CH2CH2OCOPh; 3b: R1 = iOct, R2 = CH2CH2Cl). The synthesis consisted of three consecutive steps: (i) quantitative addition of hydrogen iodide to the first vinyl ether into an adduct [CH3CH(OR1)l]; (ii) propagation of a second vinyl ether from the adduct in the presence of zinc iodide; and (iii) quenching the resulting AB‐type heterodimeric living intermediate with a carbanion [θC(COOEt)2CH2CH2OCHCH2] carrying a vinyl ether group. The HI/ZnI2‐initiated living cationic polymerization of 3a and 3b yielded narrowly distributed polymers {article}{empty}{document}( DP̄ ₙ ~ 10 ){document} consisting of a poly(vinyl ether) backbone and sequence‐regulated oligomer branches. The terminal vinyl ether function of 3 was also utilized to prepare pentamers and hexamers with controlled sequence of functional vinyl ethers by selective dimerization and chain extension reactions with HI/ZnI2.